Up to now, a heat pump cycle for a vehicle air conditioning apparatus includes a compressor, a heating interior heat exchanger, a cooling interior heat exchanger, first and second expansion valves, an exterior heat exchanger, first and second electromagnetic valves, first and second bypass passages, and an accumulator (for example, refer to Patent Document 1).
In the above heat pump cycle, the heating interior heat exchanger heats a vehicle interior air by the aid of a high-pressure refrigerant discharged from the compressor. The first expansion valve controls the opening degree of a refrigerant flow channel between an outlet of the heating interior heat exchanger and an inlet of the exterior heat exchanger. The exterior heat exchanger exchanges a heat between a refrigerant that has passed through the first expansion valve and an outside air.
The second expansion valve controls the opening degree of a refrigerant flow channel between an outlet of the exterior heat exchanger and an inlet of the cooling interior heat exchanger. The cooling interior heat exchanger cools the vehicle interior air using the refrigerant whose pressure is reduced by the second expansion valve.
The accumulator separates the refrigerant that has passed through the cooling interior heat exchanger into a gas-phase refrigerant and a liquid-phase refrigerant to accumulate the liquid-phase refrigerant as an excessive refrigerant, and supplies the gas-phase refrigerant to an inlet of the compressor. The excessive refrigerant is a refrigerant that is not necessary for operating a cooling mode, a heating mode, and the like.
The first bypass passage connects the outlet of the exterior heat exchanger and an inlet of the accumulator by bypassing the cooling interior heat exchanger and the second expansion valve. The first electromagnetic valve opens and closes the first bypass passage. The second bypass passage connects the outlet of the heating interior heat exchanger and an inlet of the second expansion valve by bypassing the first expansion valve and the exterior heat exchanger. The second electromagnetic valve opens and closes the second bypass passage.
In the cooling mode, the first expansion valve is opened so that a pressure reducing action is not caused to the refrigerant by the first expansion valve, and the first and second electromagnetic valves are closed. Further, the second expansion valve is set to a throttle opening degree causing a pressure reducing action to be exerted on the refrigerant. This produces a refrigerant circuit that causes the refrigerant discharged from the compressor to flow in the heating interior heat exchanger, the first expansion valve, the exterior heat exchanger, the second expansion valve, the cooling interior heat exchanger, the accumulator, and the compressor in the stated order.
In the heating mode, the first expansion valve is set to the throttle opening degree for causing the pressure reducing action, the first and second electromagnetic valves are opened, and the second expansion valve is closed. This produces a refrigerant circuit for causing the refrigerant discharged from the compressor to flow the heating interior heat exchanger, the first expansion valve, the exterior heat exchanger, the first bypass passage, the first electromagnetic valve, the accumulator, and the compressor in the stated order. Therefore, in the heating mode, no refrigerant passes through the cooling interior heat exchanger. For that reason, the refrigerant circuit in the heating mode is smaller in the capacity of the flow channel through which the refrigerant flows than the refrigerant circuit in the cooling mode. Therefore, the amount of the excessive refrigerant in the heating mode is larger than the amount of the excessive refrigerant in the cooling mode.
Therefore, in the heating mode, in order to reduce the amount of the excessive refrigerant accumulated in the accumulator, a part of the refrigerant that has passed through the heating interior heat exchanger is caused to flow in the second bypass passage through the second electromagnetic valve. As a result, in the heating mode, the excessive refrigerant can be accumulated in the second bypass passage. Therefore, in the heating mode, since the amount of the excessive refrigerant accumulated in the accumulator can be reduced, a size of the accumulator can be reduced.